This invention relates generally to a bottom suspension arrangement for a screw conveyer assembly, especially for the pumping of waste water, the assembly comprising a stationary cylindrical jacket having an open bottom end, and a screw conveyer mounted within the jacket for rotation about a central axis. A bottom, anti-friction bearing on the screw conveyor extends outwardly of the open bottom end of the jacket, and the suspension arrangement is connected to both the bearing and to a portion of the jacket.
In prior art screw conveyor assemblies of this type, the point of suspension for the bottom end of the jacket lies either between or outwardly of the radial load components acting at points of attachment between the suspension arrangement and the assembly. Considerable bending moments are thus exerted on the bottom end of the jacket. Experiments have shown that these bending moments, which subject the jacket to considerable pressure and cause it to buckle, can be so great that the jacket becomes deformed and assumes an oval shape causing the spiral conveyor housed within the jacket to strike or rub against the inner wall thereof. This results in premature wear of the screw conveyor assembly and a decrease in the efficiency of the pump, especially as regards the return losses of the water being pumped. And, increasing the diameter of the jacket does not solve the problem since the greater the diameter the more the disadvantageous effect with respect to the stability of the shape of the jacket.